Health Info

Paroxysmal Supraventricular Tachycardia

Definition

Paroxysmal supraventricular tachycardia (PSVT) is an abnormally fast heart beat, that begins and ends suddenly. While the normal resting heart rate is approximately 60-100 beats per minute, a PSVT attack may cause a heart rate as fast as 160-280 beats per minute. People with PSVT have attacks of tachycardia that can last anywhere from a few minutes to several hours. The abnormal heart rate originates in heart tissue other than the ventricles or lower chambers of the heart

Although PSVT is not usually life-threatening, it can cause symptoms including palpitations or feeling of heart racing, light-headedness, chest discomfort, and rarely loss of consciousness. Frequent and prolonged episodes, if not treated, can cause weakening of the heart muscle. This can result in an inability of the heart to pump effectively. This may limit a person’s physical activity. If you suspect you have this condition, contact your doctor to discuss diagnosis and treatment options.

Causes

In a normal heart, electrical impulses from the heart’s natural pacemaker, the sinoatrial or SA-node, prompt the heart to pump blood throughout the body. PSVT is the result of a “short circuit” in the electrical system of the heart. Normally there is only one electrical pathway between the upper chambers of the heart (the atria) and the bottom chambers (the ventricles). This connection is called the atrioventricular or AV-node. In some, the AV-node has two pathways which can conduct impulses, a slow pathway and a fast pathway. This creates a situation in which a feedback loop can occur called re-entry. Others have an abnormal, additional connection between the atria and ventricles called an accessory pathway leading to PSVT. Still others have an irritable group of cells in the atria that drives the tachycardia.

Risk Factors

PSVT is more common in women. It can occur at any age, but usually develops in a person's 20s or 30s. Other factors that may increase your chance of PSVT include:

Anxiety, stress, or physical fatigue

Hyperactive thyroid gland

Excessive caffeine or alcohol use

Respiratory illnesses

Low potassium and magnesium levels

Valvular heart disease

Symptoms

Diagnosis

A diagnosis of PSVT usually begins when a person notices uncomfortable attacks of rapid heart beating. Your doctor will ask about your symptoms and medical history. A physical exam will be done. The attacks may be too brief for the doctor to observe, so tests may be ordered to find the cause of the attacks. Tests may include the following:

Implantable loop recorder (ILR) is a small device that is surgically implanted under the skin of the chest and can be left in place for up to a year, or longer in some cases, in order to diagnose abnormal heart rhythms.

Electrophysiologic study
(EPS)
is an invasive heart study where electrical wires are placed in the heart through a small puncture in the veins in groin. These wires map the electrical conduction system of the heart to locate the source of the abnormality.

Blood tests to look for abnormalities in electrolytes and thyroid function.

Treatment

Treatment for PSVT involves stopping the electrical impulses causing the attacks. This can be attempted manually by your doctor using several techniques, including a guided breathing exercise called the Valsalva maneuver or carotid sinus massage. With the latter technique, the doctor applies pressure to the carotid artery in the neck for a few seconds, to reset the electrical signals, and return the heart rhythm to normal. The doctor may teach you to do these procedures to do yourself to terminate the episodes.

If manual methods fail, additional options include:

Pharmacological Methods

For people who have numerous attacks, there are medications available that can slow the conduction of electrical signals. These include:

Calcium channel blockers

Digoxin

Beta-blockers

Anti-arrhythmic medications

Surgery

A surgical procedure, known as
ablation
,
may be necessary if attacks are frequent or the if the person does not want to take medications. In this therapy, the abnormal portion of cardiac tissue causing the arrhythmia is identified and destroyed. This procedure is done in conjunction with an electrophysiology study.

Prevention

To help reduce your chance of PSVT:

Limit alcohol, smoking, and caffeine

Avoid stressful situations

Avoid excessive fatigue and lack of sleep

Revision Information

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.